40 Genetic Studies in Poultry 



referred to in Table I as Exp. 44. All of the five cockerels reared turned 

 out to be henny, while all of the five pullets tested proved to be hetero- 

 zygous. One of these henny cockerels was mated with a sister ( $ 98/16) 



c? 24/15 X ? 95/15 (cf. Exp. 40) 

 (henny) I 



cJl/16 X 2 98/16 $210/16 9235/16 $294/16 $388/16 4^?^? 



(henny) ] cf. Exp. 39) (cf. Exp. 34) (cf. Exp. 25) (cf. Exp. 37) (cf. Exp. 36) (henny) 



(J 90/17 (J 321/17 $ 150/17 $ 320/17 ? 322/17 2 .? <J 



(henny) (cf. Exp. 22) (cf. Exp. 41) (cf. Exp. 45) (cf. Exp. 42) (henny) 



who was shewn to be heterozygous in Exp. 39. From this mating all of 

 the four males produced were henny. Two of these were subsequently 

 mated to normal hens. One of them {^^ 321) proved to be heterozygous. 

 The other (</ 90) produced two henny cocks from a Brown Leghorn hen 

 in 1918, but in 1919 he failed to get any chickens. Mated with a different 

 hen he has given some chicks in the present year, but as yet they are 

 too young to be sure whether they are all henny or not\ All of his 

 three sisters proved to be heterozygous. It is possible that (/ 1/16 was 

 homozygous, but as four of his five offspring tested were certainly hetero- 

 zygous and the remaining one so far doubtful, it is more likely that 

 he was heterozygous. We attempted to breed from him again in 1918, 

 but although he was apparently a vigorous bird he failed to fertilise 

 an egg. He was killed on April 26, 1918, and histological examination 

 shewed that his spermatogenesis was abnormal. The matter is being 

 investigated further as a good deal of sterility has occurred in this 

 inbred strain. 



So far then the search for a homozygous henny bird has not been 

 successful. Of 15 birds produced by mating heterozygotes together, 

 and shewn to transmit henny feathering, 14 were definitely proved 

 to be heterozygous, the remaining one at present being doubtful. 

 Normally we should have expected five homozygotes among the 15. 

 This may of course be a chance result, but there is the possibility of 

 the homozygous bird being non-viable in the strains that have arisen 

 in the course of our experiments. Further work to decide this point is 

 now in progress. 



1 [Note added November 9, 1920.] Of the four cockerels reared this year all have coine 

 henny. Up till now therefore all of the six sons of ^ 90 have proved henny, and it is not 

 unlikely that he may be homozygous. It is hoped to test him further next year. 



